[committed] libstdc++: Fix test failure due to -Wnonnull warnings

[Jonathan Wakely]

This test fails in the Fedora RPM build (but not elsewhere, for unknown
reasons). The warning is correct, we're passing a null pointer.

	* testsuite/tr1/8_c_compatibility/cstdlib/functions.cc: Do not pass
	a null pointer to functions with nonnull(1) attribute.

Tested x86_64-linux, committed to master.

-------------- next part --------------
commit fcc443b97e19d9c8a2d8ccdfa4cc20682165827e
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Mar 12 11:03:04 2020 +0000

    libstdc++: Fix test failure due to -Wnonnull warnings
    
    This test fails in the Fedora RPM build (but not elsewhere, for unknown
    reasons). The warning is correct, we're passing a null pointer.
    
            * testsuite/tr1/8_c_compatibility/cstdlib/functions.cc: Do not pass
            a null pointer to functions with nonnull(1) attribute.

diff --git a/libstdc++-v3/testsuite/tr1/8_c_compatibility/cstdlib/functions.cc b/libstdc++-v3/testsuite/tr1/8_c_compatibility/cstdlib/functions.cc
index 89c078ffe6f..227a7580bcf 100644
--- a/libstdc++-v3/testsuite/tr1/8_c_compatibility/cstdlib/functions.cc
+++ b/libstdc++-v3/testsuite/tr1/8_c_compatibility/cstdlib/functions.cc
@@ -30,7 +30,7 @@ void test01()
 #if _GLIBCXX_USE_C99_STDLIB
 
   long long i = 0;
-  const char* s = 0;
+  const char* s = "";
   char** endptr = 0;
   int base = 0;